Printing-telegraph exchange system



June 30, 1925.

R. D. PARKER ET AL PRINTING TELEGRAPH EXCHANGE SYSTEM Filed Deb. 23, 1922 Z Wyn mm eaV WPSJW 0 m# M? mo y m b R Patented June 30, 1925.

1 UNITED. STATES PATENT OFFICE.

RALZEMOND D. PARKER AND GILBERT S. VERNAM, 0F BROOKLYN, NEW YORK, AS- SIGNOBS TO AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORA- TION OF NEW YORK.

PRINTING-TELEGRAPH EXCHANGE SYSTEM.

Application flied December 23, 1922. Serial No. 608,778.

To all whom it may concern:

Be it known that we, RALZEMOND D. PARKER and GILBERT S. VERNAM, residing at Brooklyn, in the county of Kings and State of New York, have invented certain Improvements in Printing-Telegraph Erchange Systems, of which the following is a specification.

This invention relates to telegraph systems.

An object of the invention is to provide a printing telegraph system which is flexible and one wherein a plurality of lines terminate at a central point, where means are located for establishing connections between said lines.

In the preferred form of the invention there is provided a printing telegraph system in which a plurality of printing telegraph subscribers lines terminate at a cen tral ofiice where link circuits are located for establishing connections between the lines as desired. Each of the link circuits is arranged with supervisory means for giving an indication to the operator when the telegraphic communication has ceased.

A better understanding of the invention may be had from the following description, taken in conjunction with the accompanying drawing which illustrates the invention. In Figure 1 one embodiment of the invention is shown diagrammatically. Fig. 2 illustrates a modification of the invention.

Referring for the moment to Fig. 1, there are shown'two telegraph lines D and E extending from printing telegraph subscribers stations A and B, res ctively, which terminate at a central 0 ce at which is located a link circuit C for interconnecting the telegra 11 lines. It will be understood, of course, tiat many lines similar to D and E ma terminate at the same central ofiice, and t at a plurality of link circuits similar to C may be employed. For the sake of convenience, however, only two such telegraph lines have been shown.

Each of the stations A and B is provided with printing telegraph equipment consisting of a transmitter and a receiving printer, which, for the sake of clearness, have been shown diagrammatically. It is understood, of course, that such printing telegraph equipment comprises the usual sending (11S- tributor and its associated transmitter, which may be either of the manually operated type or the tape transmitter, while the receiving mechanism comprises a receiving distributor with a receiving printer for recording theeffects of the impulses transmitted.

Associated with the line D is a line relay 9, which controls the actuation of line lamp 10. A cut-ofi' relay 11 is also provided for severing the energizing circuit of the line relay 9. Likewise associated with the line E is a line relay 15, which through its contacts controls a line lamp 16. As 1n the previous case, the energizing circuit of the line relay 15 is severed upon the energization of a cut-off relay 17.

The link circuit C, which serves to extend one line to another, is provided with a pair of plugs 20 and 21, which are designated respectively as the answering and calling plugs, and which for the sake of clearness will be referred to as such hereinafter. There is also arranged in the link circuit C suitable means for supervising a connection after it has once been established.

Assume that subscriber A desires to be placed into telegraphic communication with subscriber B, whose line E terminates at the central station in a pair of multiple jacks 18 and 19. The subscriber A in desiring to be connected with the subscriber B actuates key 3, whereupon the circuit for relay 4 is completed over a circuit extending from battery, through the contacts of ke 3 and the winding of relay 4, to ground. he key 3, in addition to closing the energizing circuit of relay 4, may also be used for closing the ower circuit of the distributors and printer in any well known manner. Relay 4, in closing its contacts, completes an energizing circuit for line relay 9 and disconnects the call hell 5 from the tip conductor of the telegraph line D. Line relay 9, in energizing, completes an operating circuit for line lamp 10, which indicates to the operator at the central office that A desires to be connected with another station. The operator thereupon inserts the answering plug 20 into either of the jacks 12 or 13, whereupon an energizing circuit is completed for cut-tfi' relay 11. The energizing circuit of cut-ofl' relay 11 may be traced from groundedl battery, through the winding of relay 25, sleeve contact of plug 20, sleeve contact of jack 12, and the winding of cut-off -relay 11, to ground. Cut-off relay 11, in

energizing, severs the circuit of the line relay 9, which becomes deenerglzed for causing the lamp 10 to be extingulshed. Relay 25 is also energized over the circuit just/traced, and connects the batteries 6 serially with the tip and ring conductors of the link circuit ,C.

The operator may now actuate key 29, which connects the printing telegraph equipment associated therewith in series with the tip and ring conductors of the link circuit (7. With the calling plug 21 in its seat, that. is, not inserted in a jack, sleeve relay 26 is accordingly deenergized for connecting resistance 28 in bridge of the tip and ring conductors of the link circuit C, whereupon an operating circuit for the printing telegraph equipment associated with the link circuit C and that at the subscribers station is completed. As shown in Fig. 1, the printing telegraph equipment, which may be associated with the link circuit C, is common to a plurality of link circuits and may be connected with the other link circuits by the actuation of a key, such as 42. It is understood, of course, that each of the link circuits is provided with a corresponding key.

The subscriber A now operates his transmitter to transmit over the line D to the central station a characteristic group of impulses representing the number of the subscribers line desired. In the particular case chosen for illustration, the character transmitted would be representative of the line I), which extends from the central station to the subscribers station B. The transmitted character or characters will accordingly be received on the printer mechanism at the central office, which was connected with the line D upon the actuation of the key 29.

The operator, having ascertained the number of the called for line, connects the tip of the plug 21 with the sleeve of either of the jacks 18 or 19 for the purpose of testing the line to determine whether the line is busy. Should the line be busy, a circuit is completed for relay 37 extending from battery, which is connected with the sleeve contact of the connected plug of some other cord circuit through the windings of corresponding relays 26 and 27, sleeve contact of the tested jack, tip contact of plug 20, lower contact of ringing key 24, lower winding of relay 35, right hand contact and armature of relay 26 and the winding of test relay 37 to ground. Relay 37, in energizing, closes at its contact the operating circuit of a sounder 38, which indicates to the operator that the line is busy and that a connection should not be established. The operator, however, upon finding the line idle, may in sert the plug 21 into either of the multiple jacks 18 or 19 and restore key 29 to normal. The key 29 being restored to normal, the printing equipment is disconnected from the link circuit, and the tip conductor of the link circuit is again complete. The plug 21 having been inserted in the jack 18, completes an energizing circuit for sleeve relay 26 and cut-oil relay 17 extending from battery, through the windin of marginal relay 27, winding of sleeve re ay 26, sleeve conductor of plugs 20, 21, and sleeve contact of jack 18 and the winding of cut-off relay 17, to ground. Cut-off relay 17, in energizing, severs the energizing circuit of line relay 15, whereupon this relay is prevented from energizing for causing the operation of line lamp 16 upon the operation of relay 32. Sleeve relay .26, in energizing, opens at its right hand contact the energizing circuit of busy test relay 37, whereupon this relay is prevented from energizing for causing the operation of busy sounder 38. It is, of course, to be understood that -the sounder 38 may be substituted by any other well-known t pe of indicating means, such as a bell or lamp. The sleeve relay 26, in addition to the severing of the energizing circuit of busy test relay 37, opens at its left hand back contact the circuit of resistance 28, and closes at its front contact the tip conductor extending between the plugs 20 and 21. On account of the resistance of the cut-off relay 17, relay 27 is not energized when the link circuit is connected with line of the type shown as E. Plug 21 being inserted in the jack of the called for line, supervisory relay 35 is also energized over a circuit extending from the negative pole of battery 6, ri ht hand contact and armature of relay 27, right hand contact and armature of relay 25, contacts of key 29 if this key is in normal position, left hand armature and front contact of relay 26, lower winding of relay 35, contacts of ringing key 21, tip contacts of lug- 21 and jack 18, and the armature and contact of relay 32 to ground. Relay 35 is accordingly energized for causing the illumination of supervisor lamp 36. The operator now actuates ringing key 24, which impresses on the line E ringing current. This ringin current traverses the line 2, passing throug the call bell 30 at the subscribers station B. The call bell 30 responds to such current for producing an audible signal to indicate to the subscriber B that the party desires to communicate with him telegraphically. The subscriber B thereupon actuates key 31, which completes an energizing circuit for line relay 32. Relay 32, in energizing, opens at its contacts the operating circuit of call bells 30, and connects the printing telegraph equip ent associated therewith withthe line E, which is now in a position to rece ve mes sages from the subscriber A. Relay 32 also in attracting its lower armature closes a c rcuit including the upper winding of d1fferential supervisory relay 35 whereby the effect of current in the ower winding is neutralized and the relay accordingly deenergized for extinguishing lamp 36. he operator bv the extin uishment of lamp 36 is advised that subscriber B has responded to the call and the printing telegraph equ pmentthereat is operatively connected with the line.

In order to advise the subscriber A that the connection has been established and that subscriber B is in a position to receive, the subscriber B operates his transmitter to send a series of impulses over the line E through the link circuit C to the line D, where such im .ulses pass through the line relay 7 contro ling the operation of the recelvlng printer mechanism (not shown). The subscriber A, upon receiving an indication from the subscriber B that the system is now in a condition for the transmission of messages between the two stations, operates the transmitter'at his station for transmitting the desired message to the station B.

If the communication has been completed between the two subscribers A and B and it is desired to signal the operator that the link circuit C may now be taken down, the subscribers open their respective keys 3 and 31 for causing the decnergization of the associated relays 4 and 32. Relay 4, in releasing, opens the circuit through the upper winding of differential relay 33, allowing current to flow onlv through the lower winding, and thus energizing differential relay 33, which in closing its upper contact causes the lighting of supervisory lamp 3 1, which indicates to the operator that the plug 20 can now be removed from its associated jack. This relay 33, in closing its lower contact, bridges a resistance 43 between the ring and ti conductors of the link circuit C. Likewlse, if the subscriber B opens key 31, therebv causing the deenergization of relay 32, differential supervisory relay 5 will be operated for causing the lamp 36 to be lighted. This, as in the previous case, serves as an indication to the operator that the connection may be taken down. Relay 35 also bridges the resistance 28 between the tip and ring conductors of the link circuit C. The brldging of the resistances 43 and 28 upon the energization of supervisory relays 33 and 35, respectively, between the tip and ring conductors of the cord circuit, makes it possible for either subscriber to communicate with the operator upon the actuation of key 29 for connecting the printing telegra h equipment thereat in circuit with.the tip conductor. Shouldsubscriber A desire to signal the operator before the connection is broken, key 3 would be opened and closed to caus the deenergization and energization of supervisory relay 33. Belay 33 responding to the actuation of key 3 causes the flashing of lamp 34. The operator, observing the flashing of this lamp, operates key 29 for connecting the printing equi ment in the link circuit. The subscriber may now communicate with the operator for any purpose desired, irrespective whether station B has disconnected or not. Like operation is brought about should subscriber B actuate key 31 in a similar manner.

Assume that during the time subscriber A is transmitting a message to subscriber B the latter subscriber desires to interrupt the sending of subscriber A in which case it is only necessary for subscriber A to actuate break key 41. The operation of break key 41 opens the line extending to the central otlice and from which the open condition is received at the subscriber station A to indicate to such subscriber that B desires to reverse the direction of sending. Likewise, at station A there is shown a break key 40 for accomplishing the same purpose as that decribed in connection with break key 41.

In Fig. 2 there is shown a conductor 50, which extends to a distant telegraph station where a cord circuit similar to C may be located, and which may be utilized for connecting the conductor 50 with the local subscriber in the district in which the conductor 50 terminates. As shown in Fig. 2, the conductor 50 terminates in a. pair of ratio arms and an artificial line AL for the purpose of providing half duplex service. Associated with the ratio arms is a receiving relay 5] and a pole changer relay 52. The ole changer relay 52 has one of its windings connected with the ring conductor of jack 53, into which there may be inserted a plug 21 similar to that shown in Fig. 1. The jack 53 has associated therewith a relay 55, which controls through its left hand contact the operation of a lamp 56, while through its right hand contact the winding of relay 55 is short circuited. \Vhen the plug 21 is inserted in the jack 53, the energizing circuit of the relay 55, which extends from battery, through the tip contact of jack 53, right hand winding of relay 55, resistance 57, upper armature and contact of relay 58, and the winding of pole chan er relay 52, to the negative terminal of the attery is severed. However, when the plu 21 is inserted in the jack, a circuit is established over the sleeve contacts, which prevents relay 55 from becomin deenergized, and thereby prevents the li ting of lamp 56. In the ty 0 of circuit s lOWIl in Fig. 2, owing to the ower resistance of the winding of relay 55 to which the sleeve of the cord circuit is connected, marginal relay 27 for this type of line is energized. Relay 27, in opening its contacts, disconnects the batter 6 from the ti condoctor of the link circuit and esta lishes u on the closure of its contacts the closure 0 the link circuit, excluding battery 6. When the link circuit is connected with the line 50, which terminates in the ratio arms and accordingly in the jack 53, and the transmitter at the station A is operated, pole changer relay 52 responds to the o eration of the transmitter thereat for app ying to the apex of the ratio arms impulses in accordance with those transmitted, due to the operation of the transmitter at the station A. Accordingly, such impulses will be transmitted over the conductor to the distant station, where such impulses pass through a receiving relay corresponding to relay 51, which causes the deenergization and energization of relay 58 in accordance with the received signals. Accordingly, impulses will be repcate to the subscriber B through the associated link circuit in accordance with those transmitted from the station A. There is also shown in Fig. 2 associated with the pole changer rela 52, a repeating sounder 60, which respon s to the operation of the pole changer relay 52.

Should it be desired to signal to the operator at the central station, where the jack 53 is located, an impulse would be transmitted over conductor 50 to operate receiving relay 51. Relay 51, responding to such impulse, causes the deenergization of relay 58, and accordin ly the openin of the energizing circuit 0 relay 55. Re a 55 thereupon releases its armatures to lig t lamp 56 and short circuit its own winding. he short circuiting of its winding prevents the reenergization of relay 55 upon the operation 0 rela 58, whereby lamp 56 remains lighted until the answering plug is inserted in jack 53. Relay 58 in opening its lower contact removes the short circuit from the lower windin of relay 52 whereupon the armature of t is relay remains in the osition shown in the drawing until the direction of sending is reversed.

It is apparent from the previous description that the present invention provides an arrangement of apparatus whereby it is possible to have a plurality of printing telegraph subscribers connected by suitable conductors to a central station, where link circuits are located for connecting the lines one with another. It is obvious that such an arran ement facilitates materially the telegraphic communication, and lessons the cost of such installations in that it does not require the installation of a separate line between the several subscribers. Also, it permits of a subscriber being connected with another subscriber whose line terminates at a central station 'where link circuits are located.

What is claimed is: I 1. In a printing telegraph exchange system, a. plurality,of subscribers stations,

printing telegraph equipment located at I each of said stations, a central oflice, signaling conductors connectin said stations with prise the operator at the central station that connection is desired with another line, a link circuit at said central oflice, a receiving printer, and means operative for connecting said printer with said link circuit, and said printer being thereby rendered responsive to the operation of the printing telegraph ecpliipment at the calling subscribers station w en said link circuit is connected with the line thereof to record the number of the party desired.

'2. A printing telegraph exchange system comprising a plurality of stations where printing telegraph e uipment is located, a telegraph line extendlng from each of said stations and terminating at a central station, a link circuit at said central station for establishing a connection between said lines, a telegraph mechanism at said central stations, means for associating said mechanism with said link circuit, a source of current for said telegraph mechanism, and means operative upon the connection of said link circuit with a calling line for connecting said source of current with said link circuit and said'telegraph mechanism.

3. A printing telegraph exchange system comprising a plurality of stations where printing telegraph equipment is located, a telegraph line extending from each of said stations and terminating at a central station, a. link circuit at said central station for establishing a connection between said lines, a telegraph mechanism at said central stations, means for associating said mechanism with said link circuit, a source of cur rent for said telegraph mechanism, means 0 erative upon the connection of said link circuit with a calling line for connecting said source of current with said link circuit and said telegraph mechanism, and

means responsive to the connection of said link circuit with the called for line to establish the continuity of said link circuit.

4. In a printing telegraph exchange system, a plurality of subscribers stations, printing telegraph equipment at each of said stations, a central oflice, signaling condue tors connecting said subscribers stations with said central oflice, link circuits at said central oflice for extending said signaling conductors, a differential relay in each end of said link circuits responsive to the disconnection of said printing telegraph equipment from the connected signaling conductors, and a signaling device operated by said relay for indicating to the operator that the communication between the connected parties has been completed.

5. A printing tele aph exchange system comprising a plura ity of stations where rintin tele raph e uipment is located, a Fele ragh lin c a extending from each of said stations and terminating at a central oflice, a link circuit at said central ofiice for extending said lines, a signaling device at each of said stations, means in said link circuit for impressing on the connected line current to operate said signaling device, and means responsive to the connection of said printing telegraph e uipment with the km for disconnecting sai signalinlg1 device.

6. A printing tele ph exc ange system comprising a plura ity of stations where printing telegraph equipment is located a telegraph line extending from each of'sald stations and terminating at a, central oflice, a link circuit at said central oflice for establishing a connection between said lines and arranged to permit the transmission of direct current telegraph signals between the connected stations, supervisory means n said link circuit, and means at each of said stations for causing the intermittent operation of said supervisory means {or recalhng the operator after a communicatlon has been completed.

7. A printing telegraph exchange system comprising a pluralit of stations, printin telegraph equipment ocated at each of sai stations, telegraph lines connecting said stations ,with a central oflice, a link circuit at said central ofiice for establishing a connection ,between said lines, printin equipment associated with said link circuit, a ke for connecting said printin telegrapli equipment in series with the tip-and ring conductors of said link circuit and meanseflective upon the operation of said telegraph key for permitting the operation of said' printer equipment at the central ofiice upon.

the operation of said printing telegraph equipment located at the subscriberls station. a v 8. A printing telegraph system comprismg a-plurallty of stations where printin te egraph equipment is located, a telegrap line extendin from each of said stations to a central station, normally open link circuits at said central stations for interconnectin said l1ne' telegraph mechanism associated with said link circuits, and means responsiye to the connection of said link circuit w1th a. calling line for completing the cir- 9. A printing telegraph exchange system comprising a plurality of stations where printing telegraph mechanism is located, a

telegraph line extending from each of said 7 stations to a central station, normally open link circuits at said central stations, for establishin connections between said lines, a source 0 signaling current at said central station, and means operated upon the connection of said link circuit with a calling and a called for line for completing the continuity of said link circuit and connecting said source of current with said link circiit,i 1 h h 1 printin tee a exc an es sterm, a plurality of su bs ribers stitioiis, printing telegraph equipment located at each of the statlons, signaling conductors connectin said stations with a central station, a te egraph'line equipped for duplex operation, also terminating at said centralstation and extending to another central station, and means at each of said central stations for establishing circuits between; said telegraph line and said signaling con-' ductors. v

11. In a printing telegraph exchange system, a plurality of subscribers stations,

printing telegraph equipment located at central station to another station, inter-- changeable means for connecting said signaling conductors with said telegraph line, a source of signaling current associated with said means, and means responsive to the connection of said means with .saidtelegraph line for disconnecting said source of current. V

12. A printing telegraph, exchange system comprising a lurality ofstations where printing telegrap equipment 0 erative on direct current signals is locate telegraph lines connecting said stations wit a central station, means atsaid central station for connecting any "one or the telegraph lines with any othertelegra h line and for permitting the passage 0 direct current signals between the connected lines, and means associated with said link circuit for ermitting the supervision of any connections I which may established.

In testimony whereof, we have si ed our names to this specification this 22n day of December, 1922.

RALZEMOND D. PARKER. GILBERT S. VERNAM. 

